1. Field of the Invention
The present invention relates to a plasma ignition device used for an ignition of an internal combustion engine.
2. Background Art
An ignition performance can be enhanced by a plasma ignition device for an internal combustion engine that ejects a plasma jet into a compressed mixture owing to a capability of providing large ignition energy to the compressed mixture. However, in a case where a spark plug gives off an erroneous spark because of an external variance, the plasma ignition device ejects a plasma jet erroneously and gives damage to the engine. Also, because energy is large, when the ignition device is operated all the times, there arises an inconvenience that the spark plug wears out quickly and power consumption is increased. In order to eliminate such an inconvenience, energy (plasma current value and discharge time) to be provided to the spark plug of the plasma ignition device is controlled according to running conditions of the internal combustion engine as is disclosed in JP-A-6-66236.
The plasma ignition device described above, however, has a problem that an electronic component in the ignition device, such as a rectifying diode, is broken by an eddy current when the center electrode of the spark plug is shorted out with a power supply system, such as a battery.